Apparatus for machining an internal cylindrical surface



Feb. 23, 1954 APPARATUS FOR- MACHININ Filed NOV. 18, 1948 W. H. SHELEY G AN INTERNAL CYLINDRICAL SUFFACE 5 SheetsSheet 1 Feb. 23, 1954 w. H. SHELEY 2,669,888

APPARATUS FOR MACHINING AN INTERNAL CYLINDRICAL SURFACE File-d Nov. 18, 1948 3 Sheets-Sheet 2 FACE W. H. SHELEY Feb. 23, 1954 APPARATUS FOR MACHINING AN INTERNAL. CYLINDRICAL SUR 5 SheetsSheet 3 Filed Nov. 18, 1948 Patented Feb. 23,1954

ABBA ATU OR M CYLINDRIC corporation ofDelavvare HINING AN INTERNAL AL SURFACE,

Wayne H; Sheley, Anderson, Illfl, assignor to General Motors Corpiiration; Detroit, Micki, a r

Application November 18, 194.8,SerialNc. 60,883 i 1 Claim. (01; 7'7-4)- 'I'his invention relates to apparatus forcounterboring metalpieces and its object is to providealmachine which will facilitate the finish cutting of a hole in a flat metal piece concentric to a finished cylindrical surface thereof. This machine provides a workholder having a cylindrical opening which receives the. finished surface of the workpiece, a clamp which forces the piece against the holder and pushes the holder and workpiece together relative to a rotating cutting tool, said movement being opposed by springs which, during retraction o'fthe clamp, return the workholder to normal-position.

Further objects and advantages of the present invention will be apparent from the following description, reference beinghad to the accompanying' drawings, whereina preferred embodiment of the present invention is clearly shown.

Inthe drawings:

Figs. 1 and 1Atogether constitutea front view .i

of'the machine.

Fig. 2 is a side view thereof: 1

Fig. 3 isa sectionalview on line 3--3 of Fig. 2.

Figs. 4 and. 5 are sectional views, respectively, on lines 4-4 and 5-5 of Fig. 3.

Fig. 5A- is-afragmentary View inthe direction of arrow 5A of Fig. 5'.-

Fig. 6 is-a, sectional viewon line.66.0f Fig. 5 showing the workholder, workpiece and. clamp.

Fig. 71's a side view, partlyinlongitudinalsec tion. of a three-bit cutter.

Fig. 8is aplan view thereof.

Figs. 9 and 10-are fragmentary, side views taken in thedirection of arrows 9 and [0, respectively; of Fig. 8.

Fig. 11. is a fragmentary, longitudinal, sectional view of a workpiece upon which the threebit cutter operates.

The machine. frame shown in Figs. 1 and 2 comprises a base which includes horizontal plates and 2| and side plates 22 which are welded together and a frame which includes a horizontal plate 23, side plates 24 and cross plates 25, 2'6, 2'! which are welded together.

A plate 22 provides a hinge block 28 which-a pinzavconnects with lugs 30 zofa plate $3 11 which supports an electric motor, 32' which drives a multigroove pulley. 33 connected by belts fit with a multigroove pulley. 35. To theright of right plate 22 there extends an integral lug 36 (Figs. 1A andZ) which receives ascrew 31 threaded through nuts 38 andpassing through 2. lug 3-9 of plate 3!. By adjusting the nuts38, the plate 3! i's'--adjusted relative to the hinge pin 29and the belts 34 are tightened.

Pulley 35 (i ig. 3) drives a boring head having ashaft lil journaled in a bearing fiance and driving a disc weaving a hole at slightly eccen trio (on the order of .004- to the axis oishaft 4c and receiving a cylindrical pilot 44 integral with a knurled disc 45 and eccentric" thereto. Disc 45 has a tapped hole 46 coaxial with the periphery thereof into which issecured-a stud 41 carrying a cutter bit 4&for finishc-uttinga holein aworkpiece W having previously finished cylindricaland plane surfaces 58 and" 5! respectively, the plane surface El being a right" angle to theaxis of the cylindrical surface. Thefunw tion of the hit ill is to finish cut acylindrical surface 52 concentric with cylindrical'surfaoc50:

ihe diameter of surface 52 is accuratelywdeter mined by the angular position of disc 45 relative to disc 42.

and disc 12 is a purchasedunit.

To the platezfi' (Figs. 1 and 2) thereisattached a bracket to comprising welded plates 6!, 52 and 53. The bearing-frame (Fig; 3) is attachedto plate 6| by nuts 04aand screws 6d which are attachedto the-plate 5i and which are received by holes in the frame M, said. holes being of such diameter as to-permit later-a1 adjustment of" the frame 4! relative to plate El adjustment is effected by turning-of screws 55 threaded through bars attached to plate 6t and abutting the frame 41. Screws 65 are fixed in adiusted position by lock nuts '61.

in upper position of ring. 17. as shown in ;Fig;.; fi. are above the cutter bit 48..

Plate. 16 in its; lower. position is. closely Lateral adjustment of frame 4! relative to plate .61 at right angle some jacent to a collar 90 which screws 9I secure to rod 10. Springs 92 urge the plate 16 upwardly to cause bushing 14 to engage a collar 93 which screws 94 secure to rod 19. Springs 92 are located by buttons 95 which are screwed into plate 16 and by tubes 96 having flanges 91 attached to plate 63. The lower ends of springs 92 press against discs 98 attached to screws 99 threaded through discs I09 attached to tubes 95. By turning the screws 99, the compression of springs 98 is adjusted and lock nuts I8I are tightened against discs I88.

Plate 26 supports a cylinder III] of a servo motor such as described in the application of W. A. Fletcher, Serial No. 781,799, filed October 24, 1941, Patent'No. 2,580,151, January 1, 1952. The rod III is connected with a piston in cylinder H8. Compressed air is admitted by a valve, not shown, to the upper side of the piston for downward movement of rod III or to the underside of the piston for upward movement of the rod. Downward movement of the rod II I is retarded hydraulically to obtain a relatively slow feeding of the workpiece to the cutter bit and retraction of the rod is effected more rapidly by means disclosed in the Fletcher application. The rod III has a thread bore H2 engaged by a bushing II3 which is secured in the required position of axial adjustment by a lock nut H4. A screw H5 having a spherical head H5 passes through bushing H3 and a nut H1 attached to a clamp I25. Nut II1 has a spherical socket receiving the head H8 of screw H5. Bushing H3 has a spherical socket receiving a spherical washer H8 which nuts H9 clamp against a shoulder of the screw H5. Balls I29 in a cage I2I are located between the bushing H3 and the nut H1 and transmit motion downwardly from rod III to the clamp I25. This construction provides for lateral movement of the clamp I25 which, as shown in Fig. 4, has three equiangularly spaced bosses I26 which are in align ment with bosses 89 of ring 11. Ring 11 has a recess 11a to provide clearance for a projecting part of the workpiece and clamp I25 has a recess I21 which receives another projecting part of the workpiece as shown in Fig. 3. To maintain alignment of the bosses I26 of clamp I25 with the bosses 89 of ring 11, clamp I25 has a notch I28 which receives a rod I29 attached to plate 19 (Fig. 3). The clearance between the rod I29 and the clamp I25 is such as not to interfere with the lateral movement of clamp I25 as provided by its connection with the rod III. Therefore as the clamp is lowered into engagement with the workpiece on the ring 11, its three bosses I26 will bear substantially equally upon the upper surfaces of the workpiece which is forced by the clamp into contact with the bosses 80 of ring 11.

While the clamp I25 and the workholder ring 11 are up in the position shown in Fig. 6, the workpiece is inserted between them and is seated upon the ring 11. When compressed air is ad mitted to the upper side of the piston connected.

with rod HI, clamp I25 moves down to press the workpiece against the ring 11 (Fig. 3). Then the clamp and the ring move down together to cause the workpiece to be engaged by the rotating cutter bit 48 which finishes the cylin drical surface 52 of the workpiece concentrically with the cylindrical pilot surface 59 and at right angle to the plane surface 5I of the workpiece. As the workpiece is fed against the bit, the downward movement of the ring 11 is resisted by com- 'pression of the springs 92 whose initial compression can be adjusted by screws 99 to obtain, in conjunction with the hydraulic retarding means referred to, the proper rate of feed of the workpiece against the cutter bit.

The venting of the upper side of the piston connected with rod III and the admission of compressed air to the underside of said piston causes the ring 11, workpiece and clamp I25 to rise together and the separation of the clamp from the workpiece W after the bushing 14 of plate 19 engages the upper stop collar 93. The machine attendant then unseats the workpiece from the ring and pushes it upon the plate 21 (Fig. 2) which serves as a chute to direct it toward a bin.

For machining a workpiece such as W (Fig. 11), three hits I49a, I495, i480 are used. These are mounted on a post I41 integral with a disc corresponding to disc 45 (Figs. 3 and 5) having an eccentric pilot 49. The eccentricity relation of pilot I43 to disc M5 is shown in Figs. '1-10 by dot-dash line E45 representing the center line of disc I45 and 143' representing the center line of pilot MB. This same relation exists between pilot 43 and disc 45. Mark 145 on part I45 (Fig. is an index cooperating with a scale (not shown) on part 92 to show the position of part I45 relative to part 42. Part 45 has a similar index mark.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

in a device of the character described the combination comprising, a workholder; clamping means for clamping a workpiece to said holder; stationary tooling means for operating on the workpiece; a pneumatic device for sequentially operating the clamping means and then while holding the workpiece in clamped position, advancing the workpiece toward the tooling means ior accomplishing the desired result; and adjustable spring means cooperating with the workholder for opposing the movement of said pneumatic means toward said tool means said yieldable means including a plurality of tubular casing members each open at one end and spaced from the workholder, a spring fitted within each of said members and extending from the open ends of the members into engagement with said workholder for supporting the same, and adjustment means adjacent the closed ends of said members and adapted to be individually adjustable for varying the action of said mounting with respect to said workholder.

WAYNE H. SHELEY.

References Cited in the file of this patent UNITED STATES PATENTS Leland Aug. 2,

pilot M5 corresponding to 

